CVE-2026-4769
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCertain devices in the WAGO System I/O Field series activate an internal diagnostic capability during the initial startup sequence. This functionality is not formally documented and becomes accessible without authentication for a brief period in the early boot phase. During this window, an unauthenticated remote attacker can gain access to the internal system processes, resulting in full system compromise.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceWAGO System I/O Field devices contain an undocumented diagnostic mode that activates during the early boot sequence. This diagnostic interface is accessible without authentication during a brief window after power-on, allowing unauthenticated remote attackers to gain full access to internal system processes and achieve complete system compromise.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the device modelCheck the device label, Web UI, or SNMP/syslog headers for 'WAGO System I/O Field' or similar product identificationAffected if The device is a WAGO System I/O Field device
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Determine boot sequence timingPower-cycle the device and observe the network services that become available in the first 30-60 seconds after power-on using port scanning or network monitoringAffected if Network services or diagnostic interfaces become accessible before the normal management interface loads
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Probe for undocumented diagnostic portsDuring the boot window, scan common diagnostic ports (TCP/23, TCP/4444, TCP/5555, TCP/8888, or any unexpected open ports) using netcat or nmap from an adjacent network segmentAffected if Any diagnostic or debug interface responds without authentication prompt
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Check for internal process accessIf a diagnostic interface is found during boot, attempt to access internal system processes or command execution features documented for authenticated usersAffected if Full internal system process access is granted without credentials
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Verify network accessibility during bootFrom an external network segment, attempt to reach the device IP during the boot window using ping, port scan, or HTTP/HTTPS requestsAffected if The device responds to network requests during the boot phase from an untrusted network
A WAGO System I/O Field device that exposes any diagnostic interface or grants internal process access without authentication during the early boot sequence is affected by this vulnerability.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply vendor firmware updates when available to disable or properly secure the undocumented diagnostic capability; in the interim, implement network segmentation and restrict access to device management interfaces during the boot phase to reduce exposure.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4769 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-4769 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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